This book assumes that you have a working PHP 4.1 development environment, and that your PHP build supports the various XML extensions discussed in this book (instructions on how to compile PHP to include this support are available in Appendix A, "Recompiling PHP to Add XML Support.")Some of the chapters in this book require additional development toolsfor example, the MySQL database server. Wherever such additional tools are required, I've included links to online resources that should assist you in obtaining and installing them.Finally, the examples and code listings in this book have been tested on both UNIX (specifically Linux) and Windows. So, the platform you're using shouldn't matter too much. In places where it does, I've made it a point to flag the section and explain the issues involved.